/Engine/Source/Runtime/Engine/Public/PrimitiveSceneProxy.h
Sets the instance local bounds for the specified instance index, and optionally will pad the bounds extents to accomodate Max World Position Offset Distance.
void SetInstanceLocalBounds ( uint32 InstanceIndex, const [FRenderBounds](API\Runtime\RenderCore\FRenderBounds) & Bounds, bool bPadForWPO )